For single items being collected this should be preferred as being more
typesafe (as the compiler can check format string and to-be-written-to
variable match) and more efficient (requiring one less parameter to be
passed).
Signed-off-by: Jan Beulich <jbeul...@suse.com>
Acked-by: Roger Pau Monné <roger....@citrix.com>
---
v2: Avoid commit message to continue from subject.
---
drivers/block/xen-blkfront.c | 43 +++++++++++++++++++------------------------
1 file changed, 19 insertions(+), 24 deletions(-)
--- 4.7-rc6-prefer-xenbus_scanf.orig/drivers/block/xen-blkfront.c
+++ 4.7-rc6-prefer-xenbus_scanf/drivers/block/xen-blkfront.c
@@ -2208,10 +2208,9 @@ static void blkfront_setup_discard(struc
info->discard_granularity = discard_granularity;
info->discard_alignment = discard_alignment;
}
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "discard-secure", "%d", &discard_secure,
- NULL);
- if (!err)
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "discard-secure", "%u", &discard_secure);
+ if (err > 0)
info->feature_secdiscard = !!discard_secure;
}
@@ -2310,9 +2309,8 @@ static void blkfront_gather_backend_feat
info->feature_flush = 0;
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "feature-barrier", "%d", &barrier,
- NULL);
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-barrier", "%d", &barrier);
/*
* If there's no "feature-barrier" defined, then it means
@@ -2321,38 +2319,35 @@ static void blkfront_gather_backend_feat
*
* If there are barriers, then we use flush.
*/
- if (!err && barrier)
+ if (err > 0 && barrier)
info->feature_flush = REQ_FLUSH | REQ_FUA;
/*
* And if there is "feature-flush-cache" use that above
* barriers.
*/
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "feature-flush-cache", "%d", &flush,
- NULL);
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-flush-cache", "%d", &flush);
- if (!err && flush)
+ if (err > 0 && flush)
info->feature_flush = REQ_FLUSH;
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "feature-discard", "%d", &discard,
- NULL);
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-discard", "%d", &discard);
- if (!err && discard)
+ if (err > 0 && discard)
blkfront_setup_discard(info);
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "feature-persistent", "%u", &persistent,
- NULL);
- if (err)
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-persistent", "%d", &persistent);
+ if (err <= 0)
info->feature_persistent = 0;
else
info->feature_persistent = persistent;
- err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
- "feature-max-indirect-segments", "%u",
&indirect_segments,
- NULL);
- if (err)
+ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+ "feature-max-indirect-segments", "%u",
+ &indirect_segments);
+ if (err <= 0)
info->max_indirect_segments = 0;
else
info->max_indirect_segments = min(indirect_segments,
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